Changes in trabecular bone score and bone mineral density following allogeneic hematopoietic stem cell transplantation

Purpose: It has been demonstrated that bone mineral density (BMD) loss is substantial within the first 12 months after allogeneic hematopoietic stem cell transplantation (alloHSCT). Declines in BMD showed a disproportionate cortical bone loss even though trabecular bone is metabolically more active than cortical bone. This finding suggests a unique mechanism. However, the structural bone deficits after alloHSCT have not been well characterized. The trabecular bone score (TBS) has emerged as a method to assess bone microarchitecture. The aim of this study was to evaluate the changes in BMD and TBS in patients who received alloHSCT with follow-up of two years. Methods: All patients 18 years and older who received a11oHSCT between 2009 and 2015 at Seoul St. Mary's Hospital, Korea were included. They were segregated into a first group (A, n = 24) that was evaluated for BMD at the time of alloHSCT and 12 months posttransplant and a second group (B, n = 44) that was evaluated for BMD at 12 and 24 months following a11oHSCT. Results: Subjects in group A experienced a decrease in BMD at the femoral neck and total hip between the time of transplantation and 12 months posttransplantation: 0.056 +/- 0.057 (5.48%) and 0.072 +/- 0.063 (6.84%), respectively. Subjects in group B experienced an increase in BMD at the lumbar spine and total hip between 12 and 24 months post-alloHSCT: 0.047 +/- 0.064 (4.90%) and 0.017 +/- 0.045 (2.16%), respectively. In group A, TBS at 12 months post-alloHSCT decreased 0.028 +/- 0.067 (1.92%) from the baseline (p = 0.086). In group B, TBS at 24 months post-alloHSCT increased 0.010 +/- 0.049 (0.78%) from the 12 months post-a11oHSCT evaluation (p = 0.149). TBS change was positively associated with BMD changes at all measured sites. The cumulative dose of glucocorticoid therapy was associated with loss of BMD at all measured sites and TBS. In addition, the dose of total body irradiation (TBI) was negatively associated with TBS. Conclusions: In summary, this study delineated longitudinal microarchitectural changes in bone structure occurring in the context of a11oHSCT. TBS change per 12 months was insignificant during the two years following alloHSCT. Therefore, our data represented disproportionate cortical bone loss in the context of the micro architecture.